Transient and Dynamic Stability Analysis

NREL researchers are investigating the impact of high penetrations of wind and solar
power on the frequency response and transient stability of electric power systems.

The stability of North American electric power grids under conditions with high penetrations
of wind and solar power is a concern and possible impediment to reaching Department
of Energy renewable energy goals.

There is general concern in the power system industry about the degradation of frequency
response over the past two decades because of factors such as the withdrawal of primary
or governor response shortly after an event due to load control action, the lack of
in-service governors on conventional generation, and the unknown and changing nature
of load frequency characteristics. Large penetrations of nonsynchronous or inverter-based
generation (such as wind turbines and solar photovoltaics) further contribute to these
concerns. Without special operation or controls, these plants do not participate in
the regulation of grid frequency. Therefore, when nonsynchronous generation displaces
conventional synchronous generation, there is potential for adverse impacts on overall
frequency response.

The impact of significant penetrations of renewables on large-scale transient stability
is also of concern. Large penetrations of inverter-based wind and solar generation
have the potential to alter system stability as a result of changes in angle/speed
swing behavior due to reduced inertia, changes in voltage swing behavior due to different
voltage control systems, different power flow patterns, and displacement of synchronous
generation at key locations.

Projects

In this project, researchers are evaluating the impact of concentrating solar power
plants on grid reliability. The goal is to identify renewable energy penetration levels
and mixes, severe disturbances, and load conditions in which grid performance and
reliability could be enhanced with frequency-responsive controls on concentrating
solar power plants.

In this project, frequency response and system inertia impacts will be investigated
based on measurement-validated power grid models and high PV-penetration scenarios.
In addition, remedial options to address low inertia and reduced frequency response
will be developed and validated.